In a typical cellular radio system, wireless terminals (also referred to as user equipment unit nodes or UEs, and/or mobile terminals/stations) communicate via a radio access network (RAN) with one or more core networks. The RAN covers a geographical area which is divided into cell areas, with each cell area being served by a radio base station (also referred to as a RAN node, a “NodeB”, and/or enhanced NodeB “eNodeB”). A cell area is a geographical area where radio coverage is provided by the base station equipment at a base station site. The base stations communicate through radio communication channels with wireless terminals within range of the base stations.
Deployment of wireless sensors has taken place in 3GPP networks. In this type of communication (termed herein Machine To Machine or M2M communication, or Machine Type Communication or MTC), devices may consume relatively little power and may be relatively low cost. Accordingly, these devices may not have advanced processing chains in the transmitter and/or receiver. Therefore, link budgets dictating these communications may be different than normal cellular radio links between base stations and UEs. More particularly, ranges of these links are expected to be much shorter than ranges of typical UE radio links.
At least at the beginning of the deployment of wireless sensors, no additional and/or no significant additional deployment of base stations (e.g., macro or pico base stations, or relay nodes) is expected to provide additional service for these M2M/MTC wireless sensors/devices. Therefore, M2M devices located in areas with relatively poor coverage may be expected. In most cases, these devices are expected to be static. In addition, traffic is expected to be mainly on the uplink which may be a challenging radio link. To provide sufficiently error-free communication in this type of radio link, proposals have been made, for example, including longer Transmission Time Intervals (TTIs), advanced receivers at the base stations, etc.
One proposal to combat poor link budgets is significantly increased deployments of relatively small, low-power base stations (e.g., pico and/or femto base stations) and/or relay nodes in areas close to wireless sensor hotspots. Hence, it is expected that service to these devices/sensors may be provided using heterogeneous deployments including different types of network nodes, such as macro base station towers, Closed Subscriber Group (CSG) Home eNBs, pico/femto base stations, etc. It is also expected that in many of these networks, “soft-cell” features/operations may be implemented, because “soft-cell” may provide relatively smooth operation of heterogeneous networks and/or increased resource efficiency. In such systems, all cooperating base stations may be open to all of the users in the network and to a backhaul linking the cooperating base stations (typically a macro base station or tower and a number of pico/small base stations located in the macro cell area).
Notwithstanding networks/methods discussed above, there continues to exist a need in the art for improved communications for M2M/MTC devices.